Store the async-await compiled pub code directly in the repo.

sdk/lib/_internal/pub_generated/test/list_package_dirs/lockfile_error_test.dart

+import 'package:path/path.dart' as path;
+import 'package:scheduled_test/scheduled_test.dart';
+import '../../lib/src/exit_codes.dart' as exit_codes;
+import '../../lib/src/io.dart';
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+main() {
+  initConfig();
+  integration("reports the lockfile path when there is an error in it", () {
+    d.dir(
+        appPath,
+        [d.appPubspec(), d.file("pubspec.lock", "some bad yaml")]).create();
+    schedulePub(args: ["list-package-dirs", "--format=json"], outputJson: {
+      "error": contains('The lockfile must be a YAML mapping.'),
+      "path": canonicalize(path.join(sandboxDir, appPath, "pubspec.lock"))
+    }, exitCode: exit_codes.DATA);
+  });
+}